The incident occurred in front of Loknath School in Rajshahi city’s Rajarhata area around 10:30am on Saturday, Boalia Police Station OC Alamgir Hossain said.
The arrestees, Nawshad Ali and Saiful Islam, lived in a hostel in Hetem Khan area, he said.
The student front of Jamaat-e-Islami called a 36-hour shutdown in eight districts of Rajshahi division on Saturday in protest against the killing of one of its members in a gunfight with police on Wednesday.
The Boalia police chief said 14-15 Shibir men took out a sudden procession and hurled bombs targeting a police vehicle when they were surrounded by the law enforcers.
Police held the duo from the spot, he said.
In another incident, locals handed over to police a member of the organisation after giving him a good thrashing when he was trying to set a CNG-run auto-rickshaw afire at Ullapara in Sirajganj.
Mohammad Ali, 30, alias Bomaru Mohammad came pillion riding on a bike, Ullapara Model Police Station OC Tajul Huda said.
People from a nearby market chased Mohammad when he tried to set ablaze the auto-rickshaw. The driver of the bike fled leaving him behind.
He had cases against him, the OC said.